In many construction projects involving materials such as concrete and steel, gaps are left between adjacent structural elements to allow for thermal expansion and contraction, wind sway, settlement, live load deflection, and/or seismic movements of the structural elements. By permitting expansion and contraction, the gaps prevent the structural materials and/or building cladding elements from cracking or buckling. These gaps are referred to as expansion joints or movement joints and are typically sealed to prevent them from allowing the passage of water, dirt, debris, or snow, etc. into the structure and/or between portions of the structure.
Current systems for sealing exterior expansion joints in the roofs of structures typically consist of a length of flexible material or membrane that spans a length and width of the joint between adjacent elements and is attached to each side of the joint by anchor bars that are screwed or bolted to the substrate. The membrane, usually a sheet of rubber or the like, is wider than the joint itself to seal the joint and to allow for movement of the structural materials with the joint. Two designs have been developed to address the issue of debris collecting on top of the membrane and straining the seal. FIG. 1 shows a prior art example of a roof expansion joint seal 10 manufactured by Johns Manville (Denver, Colo. USA). In this design, a membrane 12 is humped up above a joint J by a foam backing 14 to seal S the joint J. FIG. 2 shows a prior art example of a roof expansion joint seal 20 manufactured by MM Systems Corporation (Pendergrass, Ga. USA). This design includes a metal cover 24 over a membrane 22, which is allowed to hang into the joint J to form the seal S. As shown in FIG. 1, the roof expansion joint seal 10 is affixed about the joint J by one or more fasteners 16 through a flange 18 of the roof expansion joint seal 10. Similarly, as shown in FIG. 2, the roof expansion joint seal 20 is affixed about the joint J by fasteners 26 through a lip or flange 28 of the roof joint seal 20.
Problems may arise with either joint seal 10 and 20 in several areas. For example, the fasteners 16 and 26 are exposed to weather conditions and the seals may fail as they deteriorate and no longer effectively anchor the seals 10 and 20 about the joint J. Additionally, the seals 10 and 20 provide only a single layer of waterproofing, increasing the chances of failure of the seals. Finally, the shape of the membrane 16 and 22, whether hanging down or humped up, makes it difficult to transition from a horizontal roof expansion joint to a vertical wall expansion joint without compromising the continuity of the seals or undertaking significant modifications to the seals 10 and 20 in the field.